Journal of Soft Computing and Information Technology

Journal of Soft Computing and Information Technology

Improving Cell-Edge User Connectivity in RIS-Assisted Wireless Networks via Cooperative NOMA and Vector Power Allocation

Document Type : Persian Original Article

Authors
Asma Bagheri 1
Mohammad Amin Karimi 2
1 Faculty of Electrical and Computer Engineering, Esfarayen University of Technology, Esfarayen, North Khorasan, Iran
2 Faculty of Electrical and Computer Engineering, Esfarayen University of Technology, Esfarayen, North Khorasan, Iran.
10.22034/jscit.2026.566609.2209
Abstract
This paper investigates and enhances the connectivity of cell-edge users in fifth-generation (5G) and beyond cellular networks by leveraging advanced technologies such as multiple-input multiple-output (MIMO) systems, reconfigurable intelligent surfaces (RIS), and cooperative non-orthogonal multiple access (NOMA). In the proposed architecture, intra-cell users act as virtual relays and, by integrating direct, cooperative, and RIS-assisted reflective links, strengthen the communication reliability of cell-edge users in critical scenarios such as vehicular communications, unmanned aerial vehicle (UAV) control, and emergency response systems. To evaluate the performance, extensive statistical-numerical simulations based on the Monte Carlo method with one hundred thousand valid realizations have been conducted. The effects of several parameters such as the number of base station antennas, the number of RIS elements, signal-to-noise ratio (SNR), SNR and interference thresholds for near-user cooperative links, target SNR thresholds for far users, power allocation vectors, channel coefficients, and Nakagami-m fading parameters are examined individually and jointly on the connection probability. Simulation results reveal that the proposed scheme significantly outperforms conventional and benchmark approaches, including orthogonal multiple access (OMA), non-orthogonal multiple access (NOMA), and cooperative variants without MIMO or RIS configurations. The proposed design achieves remarkable improvements in cell-edge connectivity under various fading environments such as Nakagami-m, Rician, Rayleigh, and even more severe conditions, thus enhancing link success probability and spectral efficiency in dense and mission-critical scenarios of future cellular networks. Furthermore, while conventional cooperative schemes utilizing relays achieve only a 73.36% connectivity probability at an SNR of 10dB, the proposed architecture achieves a stable reliability level of 99.9% at a remarkably low SNR of 3dB with substantial power efficiency. These findings highlight the exceptional operational efficiency and robustness of the proposed scheme in securing reliable communication for cell-edge users.
Keywords
Cooperative non-orthogonal multiple access (CNOMA)
Cell-edge users connectivity probability
multiple-input multiple-output (MIMO)
Nakagami-m fading
reconfigurable intelligent surfaces (RIS)
vector power allocation
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Journal of Soft Computing and Information Technology
Volume 15, Issue 3
Autumn - October
Autumn 2026
Pages 1-20